View finder system



- w Q HCH l 2,219,314

VIEW FINDERv SYSTEM Filed Mair f8, 1937 s sheets-sheet 4 Y w. c. Hooi-lVIEW FINTIQI'IR SYSTEM Filed, uy 18, 193'? sheets-sheet 5 mwm.

@$29, 1940. w. c. HocH vIEw FINDEmsYsTEM 9 Sheets-Sheet '7 A, Si'

Oct. 29, 1940. w C HOCH 2,219,314

VIEW FINDER ASYSTEM Filed Maty ifs, 1937 9 sheets-sheer 9 Patented Oct.29, 1940 lVIEW FINDER SYSTEM Winton C. Hoch, Los Angeles, Calif.,assigner to 4 Technicolor Motion Picture Corporation, Bos- A' ton,Mass., a corporation of Maine Application May 18, Y1937,1Seri'a1 No.143,308 l14 Claims. (Cl. S35- 44) This invention relates to opticalapparatus, more particularly to view finding equipment used withphotographic cameras.

' It is an object of the present invention to provide improved Viewfinders of the type producing an erect image and havinginstrumentalities for focusing, for compensating parallax between cameraand nnder objectives, and for framing the nder image in 'convenient andaccurate manner.

, In one aspect of the invention, provisions are made for convenientadaptation of the finder for use with various camera objectives ofdifferent focal lengths. Another feature of my invention is the accurateand convenient simultaneous adjustment to varying object distances ofthe parallax compensation or focus settings, or both, of the finder,with provisions to adapt these settings and the corresponding framing ofthe linder image to different camera objectives by avoiding theundesirable so-called key stoning effect inherent in commonly usediinder equipment.

l A further feature of the invention is the use of image erectingreflectors in such a manner that the nder objective can be arranged veryclosely to the camera objective, whereas the image can be convenientlyviewed at considerable distance from the camera axis.

The optical elements of a View finder of the present type comprise a.group of members whose correlation to one another and to the camerarlens is critical, Whereas other elements must not necessarily bepositioned with the same degree of 'exactness Accordingly, the inventionprovides, in another aspect thereof, for especially rigid and accuratecorrelation of the elements of the rst group, unchanged vfor modifiedcamera set ups. 1The second group of elements is mounted in a mannerpermitting adaptation to various uses; 'they are easily removable an-daccessible, and exchangeable for elements of similar optical functionbut adapted for different camera setups, for example for use withcameras not having any special protective enclosure and being commonlyreferred to as "Wild camera, or, on the other hand, for use with camerasWhich are equipped with a special soundproof enclosure called blimpJ Ifused in the last mentioned manner, my nder may be arranged in such amanner that any mechanical sound Wave transmitting connection betweencamera and blimp, by Way of the finder structure, is avoided. Thisfeature of my invention also permits the camera tobe freely shiftedwithin its blimp. Also, a viewing lens can be used as a window for theblimp,

thereby simplifying andimproving the optical and mechanical constructionof such apparatus.' Still another feature of my invention consists inprovisions for simultaneously adjusting focal plane and parallaxcompensation, correctly for y with reference to several concreteembodimentsthereof. The description refers to drawings in which:

Fig. 1 is a diagrammatic representation of the optical elementsincorporated in a practical embodiment of the invention;

Fig. 2 is a representation similar to Fig. 1, but

indicating the spatial arrangement of the elements;

Fig. 3 is a perspective vieW of a motion picture camera arrangementaccording to the invention; Fig. 4 is a plan vieW of the camera shown inFig. 3, with the camera lens hood in horizontal setcion; 1 y

Fig. 5 is an isometric View of an embodiment of the iinder objectivemovement and the matte arrangement according to the invention;

Fig. 6 is a side elevation seen in direction VI indicated in Fig. 4;

Fig. 'I is a side elevation, partly in vertical section, seen indirection VII indicated in Fig. 4;

Fig. 8 is a section on line 8--8 of Fig. 4;

Fig. 9 is a section-on line 9-9 of Fig. 8;

Fig. l0 is a side elevation seen in direction X indicated in Fig. 4;

Fig. 11 is a side elevation seen in direction XI indicated in Fig. 4;

Fig. 12 is a section on line l2--l2 of Fig. 6;

Fig. 13 is an isometric view of an embodiment of the invention asapplied to a camera having a blimp; and

Fig. 14 is a plan view, partly in horizontal section, corresponding toFig. 4, but showing the embodiment according to Fig. 13.

Referring now especially to Figs. 1, 2, 3 and 13. the generalarrangement of apparatus according to my invention will first bedescribed. In these 2 Y I 2,219,314 Y -1 housing by means to bedescribed in detail later on. A view finder objective OF is mounted on afinder objective support AFl permitting axial and lateral slidingmovement relatively to camera and view finder base, as indicated byarrows a and Z in Figs. 1 and 2. Likewise mounted on base BF are areflector RI, a translucentl screen S, for example a ground glasssurface, and a frame or matte M, defining a given portion of the imageof an object eld, corresponding to the image object eld portionreproduced on the :Elm or films arranged in the camera for photographicexposure.

Adjustment of view finder lens OF in direction a is used for focusing animage, produced by that lens and framed by matte M, sharply on screen S,in well known manner. Due to the distance between the optical axes oflenses OC and OF,- although this distance is in the present instancereduced as far as possible,a parallax between the images as framed incamera and view finder, respectively, would be introduced, if lens OFwere exactly centered with respect to matte M. This discrepancy differsfor different object distances and focal lengths of camera and viewfinder lenses, and, according, to my invention, is compensated by movinglens OF and matte M relatively to each other, in the embodiment shown bymoving lens OF in direction Z perpendicular to its optical axis, thisadjustment being positively correlated with the object distance orlocation of the focal plane and the particular lens systems used.Conventional parallax adjustment devices provide for rotation of theview finder about an axis, in order to direct it towards a point uponwhich the camera lens is focused; this adjustment introduces dimensionalchanges unequal at the respective sides of the finder and thereforecommonly referred t0 as key stoning. It will be evident that myarrangement is free of any such distortional eiect.

Objective OF, matte M, screen S and, in the above described embodimentalso reflector RI, determine the relation of camera and -nder images andmust be exactly cor-related to the camera lens and to each other.Therefore, according to my invention, they are joined to form -a basicnder unit mounted on base BF which is aga-in firmly fastened to thecamera, thereby insuring maximum rigidity and accuracy. The otherelements have the purpose of erecting and enlarging the image on screenS, yat the same time permitting convenient observation thereof. Thecorrelation of .these elements is not as critical as that of the firstmentioned group, and they may be mounted with less concern about theirlocation relatively to the camera lens. In Figs. 1 and 2, these elementsare indicated as mounted in groups CF and DF. They comprise magnifyingviewing lenses VLI, VL2 and V1.3, and reflectors RI, R2, R3 and R4. Asmentioned above, reflector RI is in the preferred embodiment hereindescribed arranged Ibetween lens objective and image screen, ybut itcould also be mounted behind the screen, as indicated at RI of Fig. 1.In that case, S and M would be located in the undeviated light beamshown horizontally in Fig. 2, as indicated as S and M of that figure.

The screen S may be applied directly to lens VLI, by suitably treatingthe fiat front surface of that lens, as indicated in Fig. 2, and to bedescribed more in detail hereinafter.

In the embodiments herein shown, lens VLI, screen S integral with VLI,lens VL2 and reflector R2, form a group CF mounted with objective OF andreflector RI on finder base BF, as shown -in Figs. 3 and 13.

In the modification according to Fig. 3, the camera is used wild, thatis without protective blimp. In this instance, reiiectors R3 and R4,with lens VL3 therebetween, are mounted on box B hinged to base BF,forming the uni-t DF indicated -in Figs. 1 and 2.

In the modification laccording .to Fig. 13, unit DF is mounted on theblimp independently of the camera, lens VL3 in this instance beingarranged in front of lens reflector R, as shown at VL3 of Fig. 2, andconstituting a closure and window for the blimp aperture admitting thelight beam which carries the view nder image, as will later be describedin detail.

It will be apparent from the preceding description that my new viewfinder arrangement provides in simple and accurate manner, without usingany parts not absolutely necessary, for focus and parallax adjustment;vthat it brings the View finder objective as close to the camera lens asmechanically possible, at the same time conducting, by means of theimage erecting re flectors, -the image bearing `beam into a positionwhere it can be conveniently observed; that it provides for maximumrigidity and accuracy as far as necessary; and that, on the other hand,

it is very flexible and adaptable to ldifferent uses of the camerawithout necessitating disturbance of accuracy Iby avoiding removal andre-assemfbly of the optically critical elements of the finder.

For a more detailed description-first of a. wild camera incorporating myinventionreferen-ce is now made especially to Figs. 3 to 12.

As Vshown in these figures, view finder base BF consists vof a castframe or Ibox I from which extends downwardly a mirror support (Figs. 8and 9) having an inclined wall I8 upon which reflector R2 is mounted(Figs. 3, 11). Screwed to the top of box I is a prism support 3 havingan upwardly extending frame 4. A prism cover 5 is secured to support 3,positioning prism P which, in the present embodiment, suppliesreiiecting surface RI. Integral with box I is a mounting flange 6 havingsplit doveta-ils 'I (Figs. 4, 5, 10, 11) adapted to engage acorrespondingly shaped flange II of .camera C. By means of screws I2,I3, the dovetails can be rigidly clamped together.

A bracket I 6 is screwed to the front face of mirror extension 2 of boxI (Figs. 6, 7, 8, 9), the top face of bracket I6 being provided with adovetailed groove I'I (Fig. 8).

A lens support frame or drawer 2| slides within recess or box I (Figs.5, 6, 7, 9, l2); lenses VLI and VL2 are mounted in this frame which canbe removed from box I iby'means of knob 22. The at upper surface of lensVLI forms the previously described screen S above which matte M slidesin suitable guides 23, 24. Guides 24 may be formed by springs pressingthe matte sheet against lip 23 on the opposite side, thus firmly yetremovably holding the matte slide Within frame 2|.

Frame 4 (Figs. 3, 5, 9) has grooves 2G guiding a shield 2l having acircular opening surrounded by sleeve 28. Shield 2l extends far enoughbeyond either side of frame 4 to exclude light from the window of thellatter if it slides to the right or left.

Dovetail groove I'I of bracket I6 (Figs. 5, 8, 9) supports acorrespondingly machined intermediate slide 3I which has at its top adovetail 33 of 'conveying connection between the basic finder unit onthe camera and the viewing elements on the blimp; this arrangement isacoustically satisfactory and also does not require any change of theoptically critical finder elements if the blimp is added to the wildcamera. i

In this instance, -lens hood or matte box IH with louvers H2 is mountedon the blimp, as shown in Fig. 14.

`lin operating my view iinder, either with a wild camera, or with acamera having a blimp, the nder lens corresponding to the camera lens inuse is selected and inserted in master mount 35, as above described. Bymeans of knob 52, and latch 56, the cam and scale corresponding to thatlens are selected. Box B with hood H having been attached to hinges ll,and the matte M corresponding to the particular camera lens having beeninserted, the finder image can now be focussed by turning knob 52,whereby the proper parallax compensation will be automatically applied,as above described. 'Ihe object distance can be read on the scale ondrum 5i.

If it is desired to use a blimp, box B is detached the unit BB insteadinserted into door i113 of blimp lill. Otherwise, the operation isexactly as above described. In order to avoid opening of the blimp door,a non-sound transmitting extension of the nder setting device, operablefrom the outside of the blimp, may be provided.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modicationsand equivalents which fall within the scope of the appended claims.

I claim:

1. Photographic apparatus of the character described comprising, incombination with a camera housing and a camera objective mounted on saidhousing, a view nder base rigidly fastened to said housing, means forholding a View nder objective and mounted on said base for movement inthe direction of the axis of an objective therein, and substantiallyperpendicular thereto, means xed to said base for framing a `view finderimage, finder control means for simultaneously moving said holding meansin said two directions by amounts at which said perpendicular movementcompensates changes in parallax between said objectives upon objectivefocusing movements parallel to said axis, and means for changing theratio of said movements in order to provide correct parallaxcompensation for different view nder objectives.

2. Photographic apparatus of the character described comprising, incombination with a camera housing and a camera lens mounted on saidhousing, a view nder base fastened to said housing, an image receivingsurface mounted on said base, a View finder objective mounted on saidbase with its axis substantially parallel to said surface for twodimensional adjustment relatively to said surface within a planesubstantially parallel to that surface, means for deflecting light fromsaid objective towards said surface, and means for simultaneously movingsaid objective along, and perpendicular to its axis at a ratiocompensating the parallax change upon focusing movements along said axisby a movement normal thereto.

3. Photographic apparatus of the character described comprising, incombination with a camera housing and a camera lens mounted on saidhousing, a view finder base fastened to said housing, an image receivingmatte frame xed to said base,

a master mount adapted to receive a view finder objective arranged onsaid base for two dimensional adjustment relatively to said matte withina plane substantially parallel to the axis of said objective, means formoving said master mount in the direction of said axis andsimultaneously perpendicular thereto at a ratio compensating theparallax change upon focusing movement of y the objectivein thedirection of said axis by a movement normal thereto, means for changingsaid ratio in conformity with diierent focal distances of objectives insaid master mount, and means for selectively indicating the focusingposition of said objectives for different adjustment paths of saidmaster mount corresponding to different ones of said ratios.

. 4. A view nder of the character described comprising a base, slidinglymounted on said base a lens mount sleeve, a support plate slidinglymounted on said base for movement substantially parallel to the axis ofsaid sleeve, `a master lens mount slidingly mounted on said plate formovement substantially normal to said axis and engaging said sleeve,journaled on said plate a shaft extending substantially normal to saidaxis, having a worm drive for moving said master mount and having a camcontacting a stop on said base, and means for rotating said shaftwhereby said worm moves said mount and said sleeve normally to said axisand said cam moves said plate with said master mount parallel to saidaxis.

5. A view finder of the character described comprising a base, slidinglymounted on said base a lens mount sleeve, a support plate slidinglymounted on said base for movement substantially parallel to the axis ofsaid sleeve, a master lens mount slidingly mounted on said base formovement substantially normal to said axis and engaging said sleeve,mounted on said plate a shaft extending substantially normal to saidaxis, having a worm engaging a rack on said master mount and having twocams, a stop on said base, means for selectively associating either oneof said cams with said stop, and means for rotating said shaft wherebysaid worm moves said mount and said sleeve normally to said axis andsaid selected cam moves said plate with said master mount parallel tosaid axis.

6. In combination with view iinder apparatus of the character described,support means having a frame for passing an image bearing View nderbeam, slidably mounted over said frame a shield suiiiciently large tocover said frame over a certain range of sliding movement thereof, asleeve extending from an opening in said shield, and a lens mountmovably mounted on said support for adjustment in the direction of saidsliding movement of said shield and in the direction substantiallyperpendicular thereto, and engaging said sleeve, said shield and saidsleeve aording a light seal between said frame and said lens mountmoving laterally and axially relatively to each other.

7. Photographic apparatus of the character described comprising, incombination with a camera housing and a camera objective mounted on saidhousing, a view finder base fastened to said housing, a view nderobjective mounted on said base adjacent to said camera objective withits rear face outside of said housing, viewing aperture means laterallyof said housing. and reflecting an image formed by said nder objectiveand for 75 similar shape but at right angles to lower dovetail 32. Withdovetails 34, a master mount tube 35 moves laterally upon dovetails 33of slide 3|. Sleeve 28 extends into the interior of mount 35 and it will-be evident -that shield 2'! following the lateral movement of mount 35and sleeve 23, and the overlapping portions of mount and sleeve, form alight seal between the ycompartment containing prism P and the lensmount 35. View finder objectives VO can be inserted into mount 35,secured against rotation by groove and key arrangement 36 (Fig. 9) andcatch 3T (Fig. 8).

A shaft 4| (Figs. 5, 8, 9) is journaled in slide 3|, at right angles tothe optical axis of the objectives. By means of key and keywayarrangement 42 (Fig. 8), shaft 4| slides within worm 43 which is secureduagainst axial movement by suitable shoulders of slide 3|.

8). Likewise fastened fto shaft 4| are a scale drum and knobs 52. Atfthe other end, shaft 4| has three -circumferentia'lly grooved portions53, 54, 55 selectively engaged by catch 5G (Figs. 6 and 8) pressedtowards the shaft by lspring 5l. Upon pressing the outer end of catch 56upwardly, the shaft -is released and zcan be moved axially. In thismanner either of cams 44 or 45, or collar 46, can 'be moved oppositelinger 6| (Fig. 7), adjustably secured to bracket l5. Av helical spring62 (Figs. 6, 7, 9) presses slide 3| and 4with it .the cams against stop6 1 It will now be evident that, upon turning knob 52, one of the camswill move slide 3| relatively to bracket I6 with groove Il while, at thesame time, worm 43 moves lens mount 35 relatively to slide 3|, at rightangles to the cam movement. The lateral (worm) movement takes care ofthe parallax compensation, and the axial (cam) movement of the focusadjustment. By suitably dimensioning the cams with respect to the wormpitch, a given ratio between parallax compensation lan-d focusingmovement can .be determined.

It was found that two finder lenses having suitably selected focallengths are in general sufcient for cooperation with all cameraobjectives, the latter being grouped into short and long focus len-sesfor use with the two corresponding finder objectives. Accordingly, twocams are provided. It will be evident, however, rthat more than two Viewfinder objectives could be used and an according number of camsprovided.

Drum 5| is provided with scales, onel for each finder lens or cam,respectively, which scales are calibrated to indicate object distances.They are set with the aid of an index on sleeve 59 (Figs. 3, 4, 8); thescale corresponding to cam 45 is visible when that cam contacts stop 6|,wher-eas the scale corresponding to cam 44, previously hidden withinsleeve 59, becomes visible when cam 44 .is made operative by pullingshaft 4| forward. With the aid of these scales, the device can be set,for any one of a series of nder objectives, to a selected objectdistance for which the nder lens will then be correctly focused, and theparallax compensated.

Mattes corresponding to the iinder objectives and cams, respectively,and to each camera lens of two groups of such lenses used with arespective finder objective, are provided and can be convenientlyinserted in finder block as shown in Fig. 3. It was found that, if themattes are marked with appropriate legends, this way of changing matt-esis actually more practical, flexible and less conducive to errors thanpreviously Fixed to shaft 4| are two cams 44, 45 and a collar 46 (Figs.7,

proposed more or less automatic matte changing devices.

In order to provide for elimination of the focusing movement, ifdesired, a concentric collar 46 (Fig. 7) is provided, corresponding togroove 55 engaging latch 56 atA the other end of the shaft. Fig. 8 showscollar 46 in contact with stop 6|.

Referring to Fig. 2, the detailed arrangement of finder lens OF with itsmovements, of reector Rl (prism P), matte M, screen S and viewing lensesVLI and VL2, and of reilector R2 has so far been described.

As mentioned before, these elements are preferably mounted on the finderbase as a single rigidly correlated unit, although it would not beespecially disadvantageous to mount viewing elements VLl, VL2 and R2separately as a unit CF (Fig. 2), or to insert screen S and matte M inthe undeviated light path and mount reflector Rl either on base BF or inunit CF.

If the camera is used wild, that is without blirnp, the above mentionedviewing elements are preferably mounted on finder base Mirror box 2 forreflector R2 (Figs. 3, 10, 1l) is pro- Vvided with hinges '1| supportinga viewing mirror box B (Figs. 3, 4, 10, ll, 12) supporting reflectors R3and R4 in the manner indicated in Fig. 2. Preferably hinged at 'I2 tothe top of box B is a viewing hood H. It will be observed that hinges 1|and 'I2 are so arranged that the reflectors are easily accessible andthat, as indicated in Fig. 4, the operator can look with both eyes intohood H without being in any way inconvenienced or forced to assumepositions liable to hamper him in his activities. A catch '13, 'I4 isprovided for locking box B in operative position. Box B can be easilyremoved by lifting it from its hinges.

The eye lens VL3 is in this instance mounted in box B, betweenreflectors R3 and R4 (Figs. 10, 11, 12).

The view finder objective being very close to the camera lens would beat least partly covered by the lens hood (also called matte box) of thecamera lens. Therefore, and in order to protect the view finderobjective, I provide a hood for both lenses. In order not to diminishthe effect of the conventional camera hood and yet to present the entireobject field to the view finder, I provide a louvered partition betweencamera and finder objectives. As shown in Figs. 3 and 4, a hood 3|,fastened to the camera, covers both lenses and has blades or strips 82separating the lenses, which strips obstruct the field of vision of theview finder only slightly but effectively keep side light from thecamera lens.

If the camera is used with a soundproof enclosure or blirnp, I prefer tomount the viewing elements on the blimp wall next to the basic viewfinder unit on the camera, as shown in Figs. 13 and 14. In thesefigures, lill is the blimp housing with side wall |62 into which is seta door |03. Door |93 has an insert |04 in which viewing lens VLB ismounted (compare also Figs. 1 and 2) and which has on the outsidegrooves into which a blimp mirror box BB can be inserted. Mounted withinthis box are reflectors R3 and R4 in the manner indicated in Fig. 2, anda viewing hood BH excludes stray light.

It will be observed that lens VL3' serves at the same time as enlargingand as sound excluding element, an arrangement which reduces to aminimum the elements necessary for successful operation. Further, thereis no mechanical sound directing the light beam carrying said image fromsaid rear face around said housing to said aperture means.

8. Photographic apparatus of'the character described comprising, incombination with a camera housing and a camera lens system mounted onsaid housing, a view finder base iixed to said housing, mounted on saidbase a View nder objective parallel to said camera lens system and ascreen parallel to said lens system and said objective, means forreiecting an image bearing beam from said objective towards said screen,likewise mounted on said base a reflector for laterally deviating animage bearing light beam coming from said screen, and viewing meansremovably fastened to said housing for receiving said laterally deviatedbeam from said reflector.

9. Photographic apparatus of the character described comprising, incombination with a camera casing and a lens system mounted on saidcamera casing, a protective housing substantially enclosing said cameracasing, a view iinder base iixed to said camera casing, a view iinderobjective and a screen receiving an image from said objective mounted onsaid base within said protective housing, likewise mounted on said basea reflector for laterally deviating the image bearing light beam comingfrom said screen, and viewing means fastened to the outside of saidprotective housing for receiving said laterally deviated beam from saidreflector.

10. Photographic apparatus of the character described comprising, incombination with a f camera casing and a lens system mounted on saidcamera casing, a protective housing substantially enclosing said cameracasing, a. view iinder base xed to said camera casing, a view finderobjective and a screen receiving an image from said objective mounted onsaid base Within said protective housing, likewise mounted on said basea reflector for laterally deviating the image bearing light beam comingfrom said screen, a field lens mounted as window in a side wall of saidprotective housing for transmitting said lateral beam, and reflectingmeans mounted on the outside of said protective housing for viewing saidbeam.

11. Photographic apparatus of the character described comprising acamera housing, a camera objective mounted on said housing, a. view nderbase fastened to said housing, image receiving means on said base, aView inder objective, two slides supporting said view finder objectiveon said base, one slide movable in a direction substantially parallel tothe axis of said camera objective, and the other in a directionsubstantially normal thereto,separate control means for the respectiveslides for moving them in said directions, respectively, and means forsimultaneously actuating said control means.

12. View nder apparatus of the character described comprising incombination with a camera having a taking lens, a ba-se fastened to saidcamera, mounted on said base substantially parallel to said lens a viewnder objective,screen means substantially parallel to the axis of saidobjective and a reiiector for directing an image bearing beam from saidobjective towards said screen means, and three reflectors xed relativelyto said base in the beam emerging from said screen means at anglesdiverting said beam into the direction of the axis of said objective,said four reflectors erecting said image.

13, A view finder of the character described comprising a base,slidingly mounted on said base a lens mount sleeve, supporting meansslidingly mounted on said base for movement substantially parallel tothe axis of said sleeve, supporting means slidingly mounted on saidiirst supporting means for movement substantially normal to said axis, alens mount fastened to one of said supporting means and engaging saidsleeve, and means for adjusting said supporting means relatively to saidbase whereby said sleeve is moved by said lens mount normally to saidaxis and said mount slides in said sleeve along its axis.

14. A View finder unit comprising a base having a recess in the opticalaxis of the nder, mounted on said base in front of said recess a viewnder objective, and a eld lens unit including a frame and mountedthereon a field lens, screen surface means and a framing matte, saidframe slidingly fitting said recess, for easy removal, in position toreceive on said screen means an image produced by said objective.

WINTON C. HOCH.

